Abstract
Conventional industrial robots are unable to guarantee the inherent safety when working together with humans due to the use of rigid components and the lack of force sensation. To enhance the safety of human-robot collaboration (HRC), the new collaborative robot skin (CoboSkin) with the features of softness, variable stiffness, and sensitivity is designed and studied in this article. The CoboSkin is composed of an array of inflatable units and sensing units. The sensing units made of soft porous materials are capable of measuring distributed contact force in a real-time manner. By leveraging the foaming process, the sensing units are interconnected with inflatable units fabricated by the elastomer of which the deformation is limited by the textile wrapped around it. Variation of stiffness is enabled by adjusting the internal air pressure supplied to inflatable units, thereby changing the sensitivity of the sensing units and reducing the peak impact force. Soft porous materials endowed the CoboSkin with increased sensitivity, minimal hysteresis, excellent cycling stability, and response time in the millisecond range, which enabled sensing feedback for controlling a robot arm at different levels of stiffness. Finally, the validation of the CoboSkin for safer HRC was conducted with a robot arm to detect an unintended collision, illustrating its potential application in robotics.
Highlights
A DVANCEMENTS in human–robot collaboration (HRC) are expanding the applications of robots from the traditional production line to a more diverse range of scenarios, such as intelligent manufacturing [1], homecare [2], healthcare [3], aerospace [4], and education [5]
One of the main challenges of HRC is that safety is not always guaranteed in collaborative robots (Cobots), as they are mainly made of rigid components that can cause serious injuries to humans during physical collisions [7], [8]
A safety improvement strategy for safer HRC based on the CoboSkin was proposed
Summary
A DVANCEMENTS in human–robot collaboration (HRC) are expanding the applications of robots from the traditional production line to a more diverse range of scenarios, such as intelligent manufacturing [1], homecare [2], healthcare [3], aerospace [4], and education [5]. A safety improvement strategy for safer HRC is introduced, which is implemented based on a novel soft collaborative robot skin (CoboSkin) with the feature of variable stiffness and self-contained force sensing. This article has the following primary contributions and novelties: 1) a novel method for changing the stiffness of soft robot skin without the affecting the initial impedance of sensing units and the dynamic movements of host robots during the process of adjusting the stiffness; 2) a soft robot skin prototype (CoboSkin) with the feature of variable stiffness for the reduction of impact force during a collision and the modular design of the CoboSkin for its customized sensing function, stiffness, and dimensions to cover the cobot body; and 3) detailed manufacturing process, characterization, and experimental validation of the CoboSkin. To the best of our knowledge, this is the first approach combining multiple soft sensors into a robot skin through a foaming process
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